Describer

Filippi, Canudo, Salgado, Garrido, Garicia, Cerda & Otero 2011

Time

Cretaceous Late Santonian

Classification

Saurischia Sauropodomorpha Sauropoda Titanosauria

Diet

Herbivore

Fossilsite

Plottier Formation, Neuquén Basin, Rincón de los Sauces, Patagonia, Argentina

Info

Abstract

This paper presents a new titanosaur sauropod, collected from levels of reddish clays assigned to the Plottier Formation (Coniacian-Santonian). The holotype of Petrobrasaurus puestohernandezi gen. et. sp. nov. is a disarticulated specimen, from which teeth, cervical, dorsal and caudal vertebrae, sternal plates, metacarpals, femora, tibia, a fragment of ilium, pubis, haemal arches, and cervical and dorsal ribs have been preserved. This period is of particular interest because it saw the definitive isolation of the vertebrate faunas of Patagonia, with the separation of South America from the rest of Gondwana, a process that had begun during the Early Cretaceous. Although some of the characters observed in Petrobrasaurus gen. nov. suggest a relationship with the South American clade Lognkosauria, this new sauropod is regarded as Titanosauria incertae sedis until a more profound analysis of the Titanosauria that in which it is included is undertaken.

Holotype

Two isolated teeth (MAU-Pv-PH-449/1 and 22), posterior portion of possibly middle cervical vertebra (MAU-Pv-PH-449/37), three incomplete posterior dorsal vertebrae (MAU-Pv-PH-449/18, 19 and 26), incomplete posterior dorsal arch (MAU-Pv-PH-449/20), incomplete dorsal vertebral centrum (MAU-Pv-PH-449/27), incomplete first caudal centrum (MAU-Pv-PH-449/15), five anterior caudal vertebrae (MAU-Pv-PH-449/2, 3, 4, 5 and 6), right humerus (MAU-Pv-PH-449/36), right and left sternal plates (MAU-Pv-PH-449/10 and 25), four metacarpals (II, IV and V), one of which is incomplete (MAU-Pv-PH-449/11, 12, 13 and 35), right and left femur (MAU-Pv-PH-449/7 and , left tibia lacking distal end (MAU-Pv-PH-449/9), distal end of right tibia (MAU-Pv- PH-449/17), distal fragment of iliac peduncle (MAU-Pv- PH-449/14), left pubis (MAU-Pv-PH-449/16), fragments of haemal arches (MAU-Pv-PH-449/29, 30, 31 and 32), dorsal ribs, fragments of cervical ribs and indeterminate remains.

Etymology

Petrobrasaurus: in recognition of the Petrobras oil company for its constant collaboration in the maintenance and preservation of the palaeontological heritage in the area of Rincón de los Sauces. - puestohernandezi: refers to the Puesto Hernández oil field, where the fossil remains were found.

Locality and Age

PH 1597 locality (37°22’42.5” south / 69°04’23.1” west), Rincón de los Sauces, Patagonia, Argentina. Claystones of the Plottier Formation. Santonian (Upper Cretaceous) of the Neuquén Basin.

Diagnosis

Large sauropod dinosaur characterized by the following combination of derived features: 1) accessory posterior centrodiapophyseal lamina more developed than the posterior centrodiapophyseal lamina; 2) posterior centroparapophyseal lamina extends from the point of contact with the accessory posterior centrodiapophyseal lamina; 3) presence of a broad concave surface delimited by the bony im of the posterior centroparapophyseal lamina and a rim located on the dorsal edge of the pleurocoel; 4) presence of a deep fossa, sub-circular in outline, on a slightly concave surface delimited by the accessory posterior centrodiapophyseal lamina, the posterior centrodiapophyseal lamina, and a bony rim corresponding to the extension of the posterior centroparapophyseal lamina; 5) presence of a T-shaped anteroposterior expansion on the laminae of the neural arch (pcdl and apcdl); and the anterior caudal vertebrae characterized by: 6) the presence of a deep fossa between the spinoprezygapophyseal lamina and the postzygapophysis, bearing small fossae; 7) prespinal lamina distally thickened;  sub-circular small fossae on both sides of the base of the prespinal lamina; and 9) presence of a T-shaped anteroposterior expansion in the spinoprezygapophyseal lamina.

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